The manager asks the secretary to duplicate the document.经理让秘书复印这份文件.Your jacket's a duplicate of mine.你的夹克跟我的一样.We have duplicate keys for the front door.我们有几把相同的前门的钥匙....
工人们跪在地上，将小石子锤进去。The workers kneel on the ground and hammer the small stones in.她听到轮胎轧过石子铺成的车道，发出嘎吱声。She heard the crunch of tires on the gravel driveway.地上铺满了棱角锋利的石子。The ground was strewn with sharp-edged pebbles....
I've had a very unproductive day.我这一天什么事都没干成。One quarter of the country is reckoned as unproductive.该国四分之一的土地被认为是不毛之地.To prospect for ( oil, for example ) in an area supposed to be unproductive.盲目开掘在认为资源不足的地区盲目找 ( 如...